AFE5807ZCF Datasheet, PDF (45/74 Pages) Texas Instruments – Fully Integrated, 8-Channel Ultrasound Analog Front End

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INPUT1
INPUT2
ACT1
IN1
INM1
LNA1
ACT2
IN2
INM2
LNA2
500Ω
Mixer Clock 1
500Ω
500Ω
Mixer Clock 2
500Ω
AFE5807
SLOS703C – SEPTEMBER 2010 – REVISED MAY 2013
Cext
CW_AMPINM
10Ω
10Ω
CW _AMPINP
Rint/Rext
I/V Sum
Amp
Rint/Rext
CW_OUTP
CW_OUTM
Cext
CW I or Q CHANNEL
Structure
INPUT8
ACT8
IN8
INM8
LNA8
500Ω
Mixer Clock 8
500Ω
Note: the 10~15 Ω parasitic resistors at CW_AMPINM/P are due to internal IC routing and can create slight
attenuation.
Figure 70. A Complete In-phase or Quadrature Phase Channel
The CW mixer in the AFE5807 is passive and switch based; passive mixer adds less noise than active mixers. It
achieves good performance at low power. The below illustration and equations describe the principles of mixer
operation, where Vi(t), Vo(t) and LO(t) are input, output and local oscillator (LO) signals for a mixer respectively.
The LO(t) is square-wave based and includes odd harmonic components as the below equation expresses:
Vi(t)
Vo(t)
LO(t)
Figure 71. Block Diagram of Mixer Operation
Vi(t) = sin(w₀t + w_dt + j)+ f (w₀t)
LO(t)
=
4
p
éêë_{sin (w0 t ) +}
1
3
sin (3w₀ t ) +
1
5
sin (5w₀ t )...^ùúû
Vo(t)
=
2
p
éëcos ₍w_dt
+
f)-
cos (2w₀ t
-
w_dt
+
f)...ùû
(2)
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